FDP Strategy: Test cases

Question 1

DS FDP’s

Answer 1

Before diving into the work, remember this crucial rule:

When choosing numbers to test cases, ONLY choose numbers that are allowed by that statement!

Question 2

FDP’s — page 41

Answer 2

When you test cases in DS, your ultimate goal is to try to prove the statement INSUFFICIENT if you can.

Question 3

FDP’s — page 43

Answer 3

Step 1: What possible cases are allowed? Before I start solving, make sure that I know what restrictions have been placed on the basic problem in the question stem.

Step 2: Choose numbers that works for the statement. Pause for a moment to remind myself that I am only allowed to choose numbers for each statement that make that particular statement TRUE.

Step 3: Try to prove the statement INSUFFICIENT. Try to solve.

Question 4

When to test cases?

Answer 4

Whenever a DS sufficiency problem allows multiple possible starting points. In that case, try some of the different possibilities allowed in order to see whether different scenarios, or cases, result in different answers or in the same answer.

All problems will have one thing in common: My initial starting point is every possible number on the number line. The problem may give me certain restrictions that narrow possible values.

Question 5

Complex fractions: don’t split the denominator

Page 53, Manhattan Prep

Answer 5

A complex fraction is a fraction in which there is a sum or a difference in the numerator or denominator.

Rule: you may split of the terms in the numerator, but you may NEVER split the terms in the denominator. This is particularly useful when trying to solve for COMBOS on DS.